DESCRIPTION: The eradication of lentivirus infections remains an extremely difficult challenge. Caprine arthritis encephalitis virus (CAEV) offers an attractive, although difficult system for understanding the pathogenesis and treatment of lentivirus induced diseases of animals and perhaps those of humans. Dr. Beyer proposes a vaccine development strategy that is based on enhancing cell mediated immune responses to CAEV infection by stimulating type 1 responses, that is those mediated by type 1 (Th1) T lymphocytes. This based on findings that diseased goats have high virus titers yet mount a vigorous humoral immune response to CAEV antigens including the production of neutralizing antibodies directed against env gene products. In contrast, Dr. Beyer, and his mentor, Dr. Cheevers, have observed that asymptomatic CAEV infected goats display high CD4+ lymphoid proliferative responses and low virus titers. Vaccination will be accomplished by injecting an interferon gamma (IFN- gamma) expression vector DNA into goats to prime antigen-specific type 1 T cells and then injecting DNA of a CAEV env gene expression vector into the same animals. The goats will then be challenged with CAEV and analyzed for virus replication and development of symptoms.